title: Crystal structure of Rcl1, an essential component of the eukaryal pre-rRNA processosome implicated in 18s rRNA biogenesis.
abstract: Rcl1 is an essential nucleolar protein required for U3 snoRNA-guided pre-rRNA processing at sites flanking the 18S rRNA sequence. A potential catalytic role for Rcl1 during pre-rRNA cleavage has been suggested based on its primary structure similarity to RNA 3'-terminal phosphate cyclase (Rtc) enzymes, which perform nucleotidyl transfer and phosphoryl transfer reactions at RNA ends. Here, we report the 2.6 Å crystal structure of a biologically active yeast Rcl1, which illuminates its modular 4-domain architecture and overall homology with RNA cyclases while revealing numerous local differences that account for why Rtcs possess metal-dependent adenylyltransferase activity and Rcls do not. A conserved oxyanion-binding site in Rcl1 was highlighted for possible catalytic or RNA-binding functions. However, the benign effects of mutations in and around the anion site on Rcl1 activity in vivo militate against such a role.
authors.affiliation: Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA.
authors.forename: Naoko
authors.initials: N
authors.lastname: Tanaka
authors.forename: Paul
authors.initials: P
authors.lastname: Smith
authors.forename: Stewart
authors.initials: S
authors.lastname: Shuman
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D007716:Kluyveromyces / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012322:RNA Precursors / Q000096:biosynthesis* / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000096:biosynthesis* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics
chemical_list: D009687:Nuclear Proteins; C409342:RCL1 protein, S cerevisiae; D012322:RNA Precursors; D012337:RNA, Ribosomal, 18S; D029701:Saccharomyces cerevisiae Proteins